CROSS REFERENCE TO RELATED APPLICATIONS
FIELD OF THE INVENTION
[0002] The present invention is directed to water-based inks and coating compositions for
printing onto polyboard substrates which are primarily used for milk and juice cartons
which are free of Bisphenol A (BPA) and polymers comprising BPA.
BACKGROUND OF THE INVENTION
[0003] Presently, water-based inks used for printing onto polyboard substrates primarily
used for milk and juice cartons and other paper/board substrates are based on epoxy
esters which contain Bisphenol A (BPA) and polymers comprising BPA. However, due to
suspected toxicity, regulations are changing such that these inks can no longer contain
Bisphenol A and polymers comprising BPA.
[0004] Consequently, there is a requirement to provide water-based inks for general printing,
and in particular, for flexographic and gravure printing for polyboard substrates,
that exhibit acceptable performance and do not contain Bisphenol A (BPA) and polymers
comprising BPA.
[0005] WO 0073392 discloses the use of hybrid alkyd acrylic resins in inks for use on polythene coated
board used for milk cartons.
[0006] US2009/0297796 discloses water based screen printing inks that may be suitable for other printing
methods, primarily containing specialist pigments and a cross linker.
[0007] US 7,807,739 discloses an aqueous composition for coating substrates comprising a cross linkable
polymer, an acrylic polymer and an epoxysilane.
[0008] US2013/0309516 is directed to a coating composition having an acrylic polymer with a low glass transition
temperature that contains a cross linkable functional group and a cross linking agent.
[0009] JP3301267 is directed to water color inks containing a resin for use on corrugated fiberboard.
[0011] Finally,
CN101812255 is directed to an ink containing an acrylic resin for use on a high temperature resistance
carton.
SUMMARY OF THE INVENTION
[0012] The present invention provides a printing ink or coating composition comprising
- a) at least one self-crosslinking acrylic polymer,
- b) at least one coalescent which is an acrylic emulsion having a glass transition
temperature of less than 0°C, and
- c) at least one silicone emulsion
wherein the self-crosslinking acrylic polymer has a glass transition temperature (T
g) of greater than 0°C.
[0013] Furthermore the present invention also provides a process for preparing a coated
substrate, in particular a polyboard substrate, with the ink or a composition printed
thereon which comprises
- a) applying the printing ink or coating composition according to the invention to
a surface of the substrate and
- b) drying the ink or composition.
[0014] These and other objects, advantages, and features of the invention will become apparent
to those persons skilled in the art upon reading the details of the methods and formulations
as more fully described below.
DETAILED DESCRIPTION OF THE INVENTION
[0015] It has now been found that a printing ink or coating composition containing a self-crosslinking
acrylic polymer, a coalescent and at least one silicone emulsion can exhibit good
adhesive properties along with the requisite resistance properties when the self-crosslinking
acrylic polymer has a glass transition temperature of greater than 0°C.
[0016] The glass transition temperature herein relates to the acrylic polymer prior to self-cross
linking.
[0017] These printing inks or coating compositions are of low toxicity and are capable of
outperforming water-based inks that are based upon epoxy esters that contain Bisphenol
A (BPA) and in particular, exhibit equivalent or better physical properties in terms
of resistance to rub, water, milk, juice and line lubricant.
[0018] The printing ink or coating composition according to the present invention is substantially
free of Bisphenol A (BPA) and is advantageously substantially free of epoxy esters.
[0019] Furthermore, the printing inks and coating compositions are typically water-based
which provides for improved pigment wetting. This enables the printing inks and coating
compositions to contain less colorant thus allowing for higher amounts of varnish.
This in turn provides for maximum resistance whilst retaining color strength.
[0020] Preferably, the self-crosslinking acrylic polymer has a glass transition temperature
of between 20 to 70°C and advantageously between 40 to 60°C.
[0021] The self-crosslinking acrylic polymer is usually in the form of an aqueous dispersion
or emulsion and is typically the product of at least two monomers that react with
one another.
[0022] Furthermore, a self-crosslinking acrylic polymer refers to a one pack acrylic that
whilst under ambient cure, can achieve curing, typically via a carbonyl/amine reaction.
This can occur between ketone groups and bi- or polyfunctional amine compounds having
groups that are reactive towards carbonyl groups. These acrylic polymers exhibit enhanced
resistance properties in the resultant dried film.
[0023] The cross-linking reaction, depending upon the acrylic type, may also be initiated
by the evaporation of water upon drying, a change of pH of the vehicle or by curing
at elevated temperatures where the cross-linking reaction occurs faster or the reactive
groups are de-blocked.
[0024] One example of self-crosslinking is shown in
GB-A-2045768, which describes a dispersion which is based upon the emulsion polymerization product
of a monomer mixture primarily comprising lower alkyl (meth)acrylate monomers, minor
amounts of (meth)acrylic acid and glycidyl (meth)acrylate.
[0025] Self-crosslinking acrylic polymers may include binders selected from the group consisting
of styrene-acrylic ester copolymer, a styrene/acrylic ester copolymer containing acrylamido
groups and preferably a copolymer based on acrylonitrile, methacrylamide and acrylic
ester.
[0026] Preferably, the self-crosslinking acrylic polymer is formed from reactive monomers
which include at least one monomer selected from methyl acrylic acid (MAA), methyl
methacrylate (MMA), butyl acrylate, butyl methacrylate, styrene and methyl styrene.
Advantageously the self-crosslinking polymer is a styrene/acrylic ester copolymer.
[0027] In a preferred embodiment, the polymer is produced via a carbonyl/amine reaction,
and advantageously an acrylate with a pendent N-methylol group (such as NIBMA) is
used.
[0028] Examples of commercial acrylates formed from such monomers include Alberdingk AC2714VP,
Synthomer AM00035, Organikkimyan Orgal PO86V and DSM Neocryls XK12 & 14.
[0029] Usually, the printing ink or coating composition comprises between 20 to 60 wt% of
self-crosslinking acrylic polymer, preferably between 30 to 50 wt% of self-crosslinking
acrylic polymer and advantageously between 20 to 40 wt% of self-crosslinking acrylic
polymer.
[0030] The coalescent is also an acrylic emulsion and typically has a glass transition temperature
of less than 0°C.
[0031] Examples of commercial coalescents include Dow Lucidene 605, DSM Neocryl A2095, and
BASF Joncryl 8052.
[0032] Usually, the printing ink or coating composition comprises between 2 to 20 wt% of
coalescent and preferably between 5 to 15 wt% of coalescent.
[0033] The printing ink or coating composition also comprises a silicone emulsion.
[0034] The addition of a silicone emulsion in the formulation helps to improve the chilled
wet rub. Examples of commercially available silicones include Dow Corning DC84, DC
51, DC 209S, and Worleeadd 350. These silicones are high molecular weight polydimethylsiloxane
emulsion, containing reactive silanol groups. Alternatively a blocked reactive silicone
emulsions may be used.
[0035] Usually, the printing ink or coating composition comprises between 0.2 to 3 wt% of
silicone emulsion and preferably between 1 to 2 wt% of silicone emulsion.
[0036] The printing ink or coating composition may further comprise a colorant. Such colorants
typically include organic and inorganic pigment dispersions and dyes.
[0037] Typical pigment dispersions include Yellow 13; Orange 34; Red 122; Red 184; Red 266;
Black 15:3; Violet 23; Green 7; and Blue 15:3;
[0038] Usually, the printing ink or coating composition comprises a standard acrylic base
containing a pigment dispersion, in the amount of between 1 to 35wt% and a varnish
containing the self-crosslinking acrylic polymer, the coalescent and the silicone
emulsion according to the present invention in the amount of between 65 to 99wt%.
[0039] Preferably, the printing ink or coating composition comprises between 5 to 50 wt%
of pigment dispersion, more preferably between 20 to 45 wt% of pigment dispersion
and advantageously between 30 to 40 wt% of pigment dispersion.
[0040] The printing ink or coating compositions typically contain other additives, which
may include wetting aids, alcohols, polyethylene wax emulsions, wax dispersions, antifoams,
ammonia, defoamers, dispersants, stabilizers, silicones, rheological modifiers, plasticizers
and the like.
[0041] Examples of such additives include isopropanol and n-propanol; polyethylene wax emulsions
such as Munzing Lubraprint 2036 and Byk Aquacer 531; wax dispersions such as Munzing
Lubraprint 499, Keim Ultralube D816 and Crayvallac WW1001; antifoams such as Byk 023
and Evonik Tegofoamex 1488; and wetting aids such as Evonik TegoWet 500 and Byk Dynwet
800.
[0042] The printing ink or coating composition according to the present invention may be
used for any kind of printing but they are advantageously gravure or flexographic
printing inks or coating compositions.
[0043] The inks of the present invention have been formulated preferably for use on polyethylene
coated board substrates, e.g. polyboard, mainly used as containers (e.g. milk and
juice containers). Other substrates may include corrugated paper, paper pre-corrugation,
paper and general board.
[0044] In a particular embodiment of the invention the printing inks and coating compositions
are formulated such that they can successfully adhere to a polyethylene layer and
thus can be advantageously printed directly on "pre-formed" polyboard, as opposed
to being printed initially on the board. This eliminates the need for extruding polyethylene
over the top of a coated board after printing.
[0045] The printing inks and coating compositions of the present invention also preferably
have indirect food contact status, have been successfully migration tested and all
the materials used in therein are preferably Toxic Substances Control Act (TOSCA)
and Food and Drug Administration (FDA) approved.
[0046] The present invention also provides a process for preparing a coated substrate with
an ink or a composition printed thereon which comprises
- a) applying the printing ink or coating composition as herein described above to a
surface of the substrate and
- b) drying the ink or composition.
[0047] Furthermore the present invention further provides articles, such as milk and juice
cartons formed from the coated substrate.
[0048] The invention is further described by the examples given below.
EXAMPLES
Example 1. Formulation of inks according to the present invention.
[0049] Red, blue, black and green inks containing the materials (in weight percent) shown
in table 1 were formulated.
Example 2. Formulation of inks containing various self-crosslinking acrylic polymers.
[0050] Ink formulations containing the materials as shown in table 2 were formulated wherein
self-crosslinking acrylic polymers having varying glass transition temperatures were
incorporated therein.
Example 3. Printing and ink testing.
[0051] The inks having a print viscosity of 12 seconds, Zahn 3 cup were printed onto a treated
polyethylene board and then tested and compared to commercial inks containing Bisphenol
A.
[0052] Table 3 shows the Satra rub resistance results, after 7 days ageing for the inks
according to the present invention as listed in table 1 and commercial Flint Aquapak
comparative epoxy ester inks.
[0053] For the 3 min. Saniglide Line Lube and H
20
2 Drop Test, 1 equates to poor (i.e. complete ink removal) whilst 10 equates to excellent
(no ink removal) after 5 rubs.
[0054] Rubbing was then carried out to complete removal and the number of further rubs recorded.
All the other tests record the number of rubs required for complete removal of the
ink, a higher number of rubs being indicative of better rub resistance.
[0055] These results show that the inks described in the invention required more rubs for
complete removal than for the present commercially available inks (Flint Aquapak),
thus showing an improvement in overall resistance properties.
Example 4. Ink testing for inks containing self-crosslinking acrylic polymers with
varying glass transition temperatures.
[0056] Table 4 shows the Satra rub resistance results for self-crosslinking acrylic polymers
with various glass transition temperatures.
[0057] It is shown below in Table 4 that when self-crosslinking acrylic polymers with a
Tg less than 0°C are used the resistance properties are much lower than the inks according
to the present invention.
[0058] Ink 5 having an acrylic polymer with a glass transition temperature of 50°C is preferred.
However, ink 8 having a glass transition temperature of 25°C and ink 9 having a glass
transition temperature of 43°C also exhibit improved physical properties.
Example 5. Physical properties of the inks according to the present invention versus
comparative commercial inks.
[0059] The inks were printed on polythene extruded board and the surface treated to 40-44
dynes/cm, using a commercial Flexo press at 750ft/min using a 360#, 6.0 cc/m2 volume
anilox and photopolymer plate.
[0060] Table 5 shows that there is no deterioration of physical properties of the inks according
to the present invention.
Test Methods:
[0061]
Printability (Flexo): Visual assessment
Gloss (60°): Gloss meter reading.
Wash Up: Assessment from print crew
Resolubility: Assessment from print crew
[0062] Scratch Resistance - Proof print is laid print-side up on a hard surface and back of index finger nail
scratched across surface. Print is evaluated for level of ink removal.
Satra Wet Rub
[0063] Using a Satra rub tester (Model STM 461), a water soaked felt pad (25mm OD) under
a specified load (1.8Kg) is rotated on the surface of the print for 30 complete cycles.
The print is examined for signs of ink removal and/or surface damage.
[0064] Prints were air dried for 7 days. The prints were then tested for the following reagents:
Water, Milk, Orange Juice and Line lubricant (Saniglide) and hydrogen peroxide. For
the line lubricant and H
20
2, the line lubricant / H
20
2 is placed on the print for three minutes and the print is given 5 subsequent rubs
and assessed on a grey scale. The ink is then further tested to complete removal.
[0065] Chilled /
Humid Print and Subsequent Satra Rub Test: Prints are placed in a bucket of water and refrigerated / placed in 50°C humid conditions
for 16 to 24 hours. A test was also been carried out by spraying the prints with water
and then positioning leaving in a fridge for 16 to 24 hrs. The procedure for Satra
wet rub (water) was then followed.
[0066] Hand Wet Rub Test: Grasp proof print with thumb and forefinger at either side of the print, hands approx.
1" apart, rotate vigorously for 50 cycles under running water, prints being face to
face, to simulate repeated flexing of print. Assess level of ink removal and/or damage
to print surface.
[0067] Adhesion Tape Test: Apply Scotch 610 adhesive tape to the sample. Manually pull off the tape (slow, followed
by fast pull) in a direction perpendicular to the surface of the print. The tape is
pulled off immediately once it has been applied.
[0068] Blocking: The samples are placed in the press as requested (face to face and/or face to back)
and a pressure of 10MPa is applied at room temperature for 10 minutes. The samples
are visually inspected to ensure no blocking.
Slip Test Davenport Coefficient Of Friction
[0069] Note: Using small sled for method ASTM D.1894 - Speed 15cm/min./Sensitivity X5.
- 1. Produce proof prints of the batch under test on the specified substrate(s). Print
of sufficient width and length should be prepared.
- 2. Affix one sample of print, minimum 10 inches long, to the test bed with adhesive
tape, ensuring it is held flat, smooth and unstretched.
- 3. Cut another piece of print, using appropriate template, and affix to the underside
of the sled with adhesive tape. Ensure that the print surface is not touched.
- 4. Attach the cord to the sled, and place the latter gently onto the left-hand end
of the print on the test bed, so that it is positioned centrally between the two L-shaped
marks, with its leading edge in line with the right-hand edge of the marks. Leave
a small amount of slackness in the cord.
- 5. Press the 'Start' button (and if measuring static slip, immediately re-set the
digital display in order to ensure a false reading is not registered from start-up).
- 6. Static: Record the final (maximum) reading on the digital display, or the highest
recorded force at the beginning of the recorder trace.
- 7. Dynamic: Note the highest and lowest readings, during the period of steady movement, on the
needle scale, and record the mean of these values. If using a recorder, obtain the
average of the trace during this period.
[0070] The coefficient of static and/or dynamic friction is given by:
Where the force in grams = reading multiplied by 10 for sensitivity X1
or = reading multiplied by 2 for sensitivity X5
1. A printing ink or coating composition comprising
a) at least one self-crosslinking acrylic polymer,
b) at least one coalescent which is an acrylic emulsion having a glass transition
temperature of less than 0°C, and
c) at least one silicone emulsion,
wherein the self-crosslinking acrylic polymer has a glass transition temperature of
greater than 0°C.
2. A printing ink or coating composition according to claim 1 wherein the self-crosslinking
acrylic polymer has a glass transition temperature of between 20 to 70°C, preferably
between 40 to 60°C.
3. A printing ink or coating composition according to any one of the preceding claims
wherein the self-crosslinking acrylic polymer is (i) formed from monomers selected
from methyl acrylic acid (MAA), methyl methacrylate (MMA), butyl acrylate, butyl methacrylate,
styrene and methyl styrene; and/or (ii) a styrene/acrylic ester copolymer; and/or
(iii) formed from a carbonyl/amine reaction; and/or (iv) an acrylic emulsion.
4. A printing ink or coating composition according to any one of the preceding claims
wherein the silicone emulsion is high molecular weight polydimethylsiloxane emulsion
containing reactive silanol groups.
5. A printing ink or coating composition according to any one of the preceding claims
comprising between 20 to 60 wt% of self-crosslinking acrylic polymer, preferably between
30 to 50 wt% of self-crosslinking acrylic polymer.
6. A printing ink or coating composition according to any one of the preceding claims
comprising between 2 to 20 wt% of coalescent, preferably between 5 to 15 wt% of coalescent.
7. A printing ink or coating composition according to any one of the preceding claims
comprising between 0.2 to 3 wt% of silicone emulsion preferably between 1 to 2 wt%
of silicone emulsion.
8. A printing ink or coating composition according to any one of the preceding claims
further comprising a colorant, preferably wherein the colorant is a pigment dispersion.
9. A printing ink or coating composition according to claim 8 comprising between 5 to
50 wt% of pigment dispersion, preferably between 20 to 45 wt% of pigment dispersion,
e.g. between 30 to 40 wt% of pigment dispersion.
10. A printing ink or coating composition according to any one of the preceding claims
further comprising one or more additives selected from the group consisting of wetting
aids, alcohols, polyethylene wax emulsions; wax dispersions; antifoams; waxes, ammonia,
defoamers, dispersants, stabilizers, silicones, rheological modifiers and plasticizers.
11. A printing ink or coating composition according to any one of the preceding claims,
wherein the composition is a gravure or flexographic printing ink or coating composition.
12. A printing ink or coating composition according to any one of the preceding claims
that is water-based.
13. A printing ink or coating composition according to any one of the preceding claims
which is substantially free of Bisphenol A (BPA) and/or substantially free of epoxyesters.
14. A process for preparing a coated substrate with an ink or a composition printed thereon
which comprises
a) applying the printing ink or coating composition according to any one of the preceding
claims to a surface of the substrate and
b) drying the ink or composition; preferably wherein the substrate is selected from
polyethylene board, corrugated paper and pre-formed polyboard
15. A coated substrate prepared by the process of claim 14.
16. An article formed from the coated substrate of claim 15, preferably wherein the article
is in the form of a milk or juice carton.
1. Drucktinte oder Beschichtungszusammensetzung, umfassend:
a) mindestens ein selbstvernetzendes Acrylpolymer;
b) mindestens ein Koaleszierungsmittel, das eine Acrylemulsion mit einer Glasübergangstemperatur
unter 0 °C ist, und
c) mindestens eine Silikonemulsion;
wobei das selbstvernetzende Acrylpolymer eine Glasübergangstemperatur über 0 °C aufweist.
2. Drucktinte oder Beschichtungszusammensetzung nach Anspruch 1, wobei das selbstvernetzende
Acrylpolymer eine Glasübergangstemperatur zwischen 20 und 70 °C aufweist, vorzugsweise
zwischen 40 und 60 °C.
3. Drucktinte oder Beschichtungszusammensetzung nach einem der vorhergehenden Ansprüche,
wobei das selbstvernetzende Acrylpolymer (i) gebildet ist aus Monomeren ausgewählt
aus Methylacrylsäure (MAA), Methylmethacrylat (MMA), Butylacrylat, Butylmethacrylat,
Styrol und Methylstyrol; und/oder (ii) ein Styrol/Acrylester-Copolymer ist; und/oder
(iii) gebildet ist aus einer Carbonyl/Amin-Reaktion; und/oder (iv) eine Acrylemulsion
ist.
4. Drucktinte oder Beschichtungszusammensetzung nach einem der vorhergehenden Ansprüche,
wobei die Silikonemulsion eine Emulsion von Polydimethylsiloxan mit hohem Molekulargewicht
ist, das reaktive Silanolgruppen enthält.
5. Drucktinte oder Beschichtungszusammensetzung nach einem der vorhergehenden Ansprüche,
die zwischen 20 und 60 Gew.% selbstvernetzendes Acrylpolymer, vorzugsweise zwischen
30 und 50 Gew.% selbstvernetzendes Acrylpolymer umfasst.
6. Drucktinte oder Beschichtungszusammensetzung nach einem der vorhergehenden Ansprüche,
die zwischen 2 und 20 Gew.% Koaleszierungsmittel, vorzugsweise zwischen 5 und 15 Gew.%
Koaleszierungsmittel umfasst.
7. Drucktinte oder Beschichtungszusammensetzung nach einem der vorhergehenden Ansprüche,
die zwischen 0,2 und 3 Gew.% Silikonemulsion, vorzugsweise zwischen 1 und 2 Gew.%
Silikonemulsion umfasst.
8. Drucktinte oder Beschichtungszusammensetzung nach einem der vorhergehenden Ansprüche,
ferner umfassend ein Färbungsmittel, wobei das Färbungsmittel vorzugsweise eine Pigmentdispersion
ist.
9. Drucktinte oder Beschichtungszusammensetzung nach Anspruch 8, umfassend zwischen 5
und 50 Gew.% Pigmentdispersion, vorzugsweise zwischen 20 und 45 Gew.% Pigmentdispersion,
z. B. zwischen 30 und 40 Gew.% Pigmentdispersion.
10. Drucktinte oder Beschichtungszusammensetzung nach einem der vorhergehenden Ansprüche,
ferner umfassend ein oder mehrere Additive ausgewählt aus der Gruppe bestehend aus
Benetzungshilfsmitteln, Alkoholen, Polyethylenwachsemulsionen; Wachsdispersionen;
Antischaummitteln; Wachsen, Ammoniak, Entschäumern, Dispergiermitteln, Stabilisatoren,
Silikonen, Rheologiemodifizierungsmitteln und Plastifizierungsmitteln.
11. Drucktinte oder Beschichtungszusammensetzung nach einem der vorhergehenden Ansprüche,
wobei die Zusammensetzung eine Drucktinte oder Beschichtungszusammensetzung für Gravur-
oder Flexographiedruck ist.
12. Drucktinte oder Beschichtungszusammensetzung nach einem der vorhergehenden Ansprüche,
die auf Wasserbasis ist.
13. Drucktinte oder Beschichtungszusammensetzung nach einem der vorhergehenden Ansprüche,
die im Wesentlichen frei von Bisphenol A (BPA) und/oder im Wesentlichen frei von Epoxyestern
ist.
14. Verfahren zur Herstellung eines beschichteten Substrats mit einer Tinte oder einer
Zusammensetzung, die darauf gedruckt ist, welches umfasst:
a) Aufbringen der Drucktinte oder Beschichtungszusammensetzung gemäß einem der vorhergehenden
Ansprüche auf eine Oberfläche des Substrats, und
b) Trocknen der Tinte oder Zusammensetzung; wobei das Substrat vorzugsweise ausgewählt
ist aus Polyethylenkarton, Wellpappe und vorgebildetem Mehrschichtmaterial (Polyboard).
15. Beschichtetes Substrat, das nach dem Verfahren gemäß Anspruch 14 hergestellt ist.
16. Artikel, der aus dem beschichteten Substrat gemäß Anspruch 15 gebildet ist, wobei
der Artikel vorzugsweise in Form eines Milch- oder Saftkartons vorliegt.
1. Encre d'impression ou composition de revêtement comprenant
a) au moins un polymère acrylique à autoréticulation,
b) au moins un agent coalescent qui est une émulsion acrylique ayant une température
de transition vitreuse inférieure à 0 °C, et
c) au moins une émulsion de silicone,
dans laquelle le polymère acrylique à autoréticulation a une température de transition
vitreuse supérieure à 0 °C.
2. Encre d'impression ou composition de revêtement selon la revendication 1, dans laquelle
le polymère acrylique à autoréticulation a une température de transition vitreuse
comprise entre 20 et 70 °C, de préférence entre 40 et 60 °C.
3. Encre d'impression ou composition de revêtement selon l'une quelconque des revendications
précédentes, dans laquelle le polymère acrylique à autoréticulation est (i) formé
à partir de monomères choisis parmi l'acide méthylacrylique (MAA), le méthacrylate
de méthyle (MMA), l'acrylate de butyle, le méthacrylate de butyle, le styrène et le
méthylstyrène ; et/ou (ii) un copolymère de styrène/ester acrylique ; et/ou (iii)
formé à partir d'une réaction carbonyle/amine ; et/ou (iv) une émulsion acrylique.
4. Encre d'impression ou composition de revêtement selon l'une quelconque des revendications
précédentes, dans laquelle l'émulsion de silicone est une émulsion de polydiméthylsiloxane
à poids moléculaire élevé contenant des groupes silanol réactifs.
5. Encre d'impression ou composition de revêtement selon l'une quelconque des revendications
précédentes, comprenant entre 20 et 60 % en poids de polymère acrylique à autoréticulation,
de préférence entre 30 et 50 % en poids de polymère acrylique à autoréticulation.
6. Encre d'impression ou composition de revêtement selon l'une quelconque des revendications
précédentes, comprenant entre 2 et 20 % en poids d'agent coalescent, de préférence
entre 5 et 15 % en poids d'agent coalescent.
7. Encre d'impression ou composition de revêtement selon l'une quelconque des revendications
précédentes, comprenant entre 0,2 et 3 % en poids d'émulsion de silicone, de préférence
entre 1 et 2 % en poids d'émulsion de silicone.
8. Encre d'impression ou composition de revêtement selon l'une quelconque des revendications
précédentes, comprenant en outre un colorant, de préférence dans laquelle le colorant
est une dispersion de pigment.
9. Encre d'impression ou composition de revêtement selon la revendication 8, comprenant
entre 5 et 50 % en poids de dispersion de pigment, de préférence entre 20 et 45 %
en poids de dispersion de pigment, par exemple entre 30 et 40 % en poids de dispersion
de pigment.
10. Encre d'impression ou composition de revêtement selon l'une quelconque des revendications
précédentes, comprenant en outre un ou plusieurs additifs choisis dans le groupe constitué
d'adjuvants de mouillage, alcools, émulsions de cire de polyéthylène ; dispersions
de cire ; antimousses ; cires, ammoniac, démousseurs, dispersants, stabilisants, silicones,
modificateurs rhéologiques et plastifiants.
11. Encre d'impression ou composition de revêtement selon l'une quelconque des revendications
précédentes, dans laquelle la composition est une encre de gravure ou d'impression
flexographique ou une composition de revêtement.
12. Encre d'impression ou composition de revêtement selon l'une quelconque des revendications
précédentes qui est à base d'eau.
13. Encre d'impression ou composition de revêtement selon l'une quelconque des revendications
précédentes, qui est sensiblement exempte de bisphénol A (BPA) et/ou sensiblement
exempte d'époxyesters.
14. Procédé de préparation d'un substrat revêtu avec une encre ou une composition imprimée
sur celui-ci, qui comprend
a) l'application de l'encre d'impression ou de la composition de revêtement selon
l'une quelconque des revendications précédentes sur une surface du substrat et
b) le séchage de l'encre ou de la composition ; de préférence dans lequel le substrat
est choisi parmi un panneau de polyéthylène, du carton ondulé et du Polyboard préformé.
15. Substrat revêtu préparé par le procédé selon la revendication 14.
16. Article formé à partir du substrat revêtu selon la revendication 15, l'article étant
de préférence sous la forme d'une boîte en carton de lait ou de jus.